In general, the photographic processing of color light-sensitive materials comprises basically a color developing step and a desilvering step. A color light-sensitive material which has been exposed imagewise is first sent to the color developing step where silver halide is reduced by a color developing agent, producing silver, while at the same time, the oxidized color developing agent reacts with a color former to provide a dye image. The color light-sensitive material is sent to the desilvering step where the silver produced at the preceding step is oxidized by an oxidizing agent (generally called a "bleaching agent") and, thereafter, removed by dissolving with a silver ioncomplexing agent generally called a "fixing agent". Finally, therefore, only the dye image is formed in the color light-sensitive material. However, the photographic processing actually includes auxiliary steps, e.g., for maintaining the photographic and physical characteristics of the image, or for improving the shelf life of the image, as well as the above-described two basic steps. Examples include a hardening bath for preventing excessive softening of light-sensitive layers during the photographic processing, a stop bath for effectively stopping the development reaction, an image-stabilizing bath for stabilizing the image, and a defilming bath for removing a backing layer form the support.
The desilvering treatment can be performed by a two-step process in which the bleaching and fixing baths are separated from each other, a one-step process in which there is used a bleach-fixing bath containing both a bleaching agent and a fixing agent; i.e., the treatment is more simplified for rapid processing and labor-saving.
In general, red prussiate and ferric chloride are good bleaching agents in that they have great oxidizing power. These compounds, however, cause various problems. For example, bleaching or bleach-fixing solutions containing red prussiate as a bleaching agent release cyanogen owing to photolysis, causing pollution problems. For this reason, their waste solutions should be made completely harmless by specific techniques. Also, bleaching solutions containing ferric chloride as a bleaching agent suffer from disadvantages in that because of their very low pH values and very great oxidizing power, they are liable to corrode parts of an apparatus to which they are charged. Furthermore, during the water-washing step after the bleaching treatment, ferric chloride causes iron hydroxide to precipitate in emulsion layers, producing stains.
Other bleaching agents which have heretofore been used include potassium dichromate, quinones, and copper salts. These compounds, however, have disadvantages in that they have only poor oxidizing power and are difficult to handle.
In recent years, in view of demands for a rapid and simplified photographic processing, and for preventing pollution, bleaching solutions composed mainly of iron (III) ion complex salts, e.g., aminopolycarboxylic acid iron (III) ion complex salts, in particular, an EDTA-iron (III) complex salt have been widely used.
These iron (III) ion complex salts, however, are of relatively low oxidizing power and possess insufficient bleaching power. When bleaching solutions containing such iron (III) ion complex salts as bleaching agents are used in the bleaching or bleach-fixing treatment of low sensitivity color light-sensitive materials prepared using mainly a silver chlorobromide emulsion, bleaching can be attained to a certain extent. However, in treating high sensitivity color light-sensitive materials which are prepared using mainly a silver chlorobromide or silver iodobromide emulsion, and are color sensitized, particularly camera color reversal light-sensitive materials and camera color negative light-sensitive materials in which emulsions containing a large amount of silver are used, their bleaching power is insufficient. This causes problems such as poor desilvering and the need for a long period of time for bleaching.
Bleaching agents other than the iron (III) ion complex salts such as persulfuric acid salts are known. These pursulfuric acid salts are usually used for preparing bleaching solutions in combination with chlorides. These bleaching solutions, however, have disadvantages in that their bleaching power is much lower than those of the iron (III) ion complex salts, and they need a long period of time for bleaching.
As described above, bleaching agents which are free from the problems of pollution and corrosion of processing equipment are not suitable for use in a rapid processing of color light-sensitive materials because of their poor bleaching power. It has therefore been desired to improve color light-sensitive materials so that they can be rapidly processed even with those bleaching agents having relatively low bleaching power.
A method has heretofore been employed in which bleach accelerators, e.g., amino compounds described in, for example, U.S. Pat. Nos. 3,772,020 and 3,809,563, are added to a processing bath (a bleaching or bleach-fixing bath, or its pre-bath). However, this method still takes a long period of time to achieve sufficient belaching. Moreover, many of the bleach accelerators are difficult to present in the bath in a stabilized condition, or emit an offensive odor. Thus, the addition of such compounds to the processing bath presents problems.
The addition of known bleach accelerators to color light-sensitive materials is also disclosed in, for example, Japanese Patent Application (OPI) No. 147529/78 (the term "OPI" as used herein means a "published unexamined Japanese patent application"). This method, however, suffers from disadvantages in that the known bleach accelerators have only a poor bleach-accelerating effect, and exert adverse influences on the photographic characteristics of color light-sensitive materials. Moreover, in accordance with this method, it is difficult to sufficiently bleach high silver content color light-sensitive materials including colloidal silver layers, such as a yellow filter layer and an antihalation layer while preventing an increase in fog due to colloidal silver during storage.